Aircraft



Oct. 7, 1930.

H. PRATT AIRCRAFT Filed Maron-11, 1929 2 sweets-sheet 1 INVENTOR. Har nld EF1-aft ATTORNEYS.

H. c.4 PRATT n 1,777,992

.AIRCRAFT Y Filed March l1, 1929 um IIII| i; IZ 25 /Z Q:

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-smres PAT-ENT errlCE .fiiaaotna rsaTT, onsWnMrscoTT,MAssAcnusnTTs; nona conn yrnATTADMINIS- f Y Tna'rnrx or sain Hanonn c. PRATT, nnonnsnn AIRCRAFT Application filed March 11,1929, Serial No. 346,221.

f This invention 'relates to improvements in aircraft. Y A'llie'primary object of this invention is the provision vof anV improved heavier than air ,3; flying' machine, which comprises a construction v'adaptable for sustained flightlfby the utilization of comparativelygreat speeds, in fact so rapid thatthe air, Willinothave time tothe compressed and displaced With respect to theplane or planes. y 'ggf further and important object ofthis invention is the provision of anf improved heavier than' air fiyingmachine'in Which the Weight of the aircraftV is' sustainedby reacf 'tions resulting When one or more flat planes Y or'aerofoils thereof lare 'moved'thru theairat a very small angle of incidence, or With practically'no yangle o'fincidence, by the application: of'y mechanical power, in such manner @that ythe planes are subjected-to ararefied condition of the atmosphereon the upper surface of the plane and a compressed' condition of the atmosphere on the under'surface of the plane;y i"

:A further andjimportant object of the invention` is the provision of a heavier than air l liying'machine which comprises a novel arrangement of sustaining planes comprising a plane Vmmmted centrally above the fuselage SG'having a relatively long cord and relatively small span; the planes being preferably, flat and Without camber, and having sideflanges to' direct the air stream from the propeller lin an efficient relation under the short span sus-` taining planes. y y i L@ther objects and advantages of .this'invention will be apparent duringthe course vof thel following detailed description. s In the accompanying drawings, forminga 49 partof this specification, and wherein simi lar Nreference characters designate corre- Q sponding parts thruout the several views. Y

Figure l is a side elevation of the improvedfiying machine.

,45 "Figure is a plan view of the flying machine.

Figure 3 is a bottom plan view of the flying machine. Y f

Figurell is a s, perspectiveview of the flying 50 machine. l f

In the drawings, wherein for the purpose of illustration isshown only a preferred embodiment of the invention, the. letter A may generally designate the improved flying ma chine, Which may comprise a fuselage B, sustaining plane means C, propelling means D, and landing gear E. i

The s fuselage B is of narrow elongated stream line construction, in the form of a boat, and Water-proofed so that the machine may alight on the Water as Well as on` the land; lt tapers, as shown in Figure 3, from the forward enclin a Widening relation to a distance about onethird of the length of the fuselage from the front thereof, and there from tapers in a convergent relation to the rear end. There is a rudder l provided at the rear of the boat-like fuselage, for gue ing the craft when traveling` in Water. Fixed planes ll are provided at the extreme rear of the fuselage B, at opposite sides thereof, which are preferably flat, to prevent depression of the stern of the craft in the Water, and to aidin stability of the craft While flying.

The landing gear E is of conventional construction, and may include an axle 11a to which Wheels l2 are rotatably mounted; said axle at the ends adjacent the vWheels being connected by V arranged spars 13 With the fuselage B, at approximately the Widest portion thereof, A conventional tail skid 15 is placed at the rear under surface of the fuselage.

Referring to the sustaining` plane construction C, it is preferred to make the aircraft of the monoplane type. The single plane 2O vis flat, and the fore and `aft dimension is several times greater than the transverse or beam dimension. It is connected u on its longitudinal central axis by a plane-lille spar or supporting structure 21., best shovvnfin Figure 4 of the drawings, at a location above the fuselage, 'and particularly above kthe cabinet structure 22 thereof. This supporting structureis shown in `detail in Figure l,

Zag' rela-tion between the longitudinal center line" at the top ofthe fuselage B and the longitudinal axis of the planeQO; The plane 20 has a longitudinal beam 28 Vconnected centrally/thereof, to which the-upper ends of the said spars 23 'to 26 inclusive vare connected, in an efliciently braced relationj tical upright spare 30 and 31 are provided at the front and rear of the plane 20, being con- 'iiected at their upperends'to the middle beam 28, and at their'lower endsto the top of the fuselage Construction, preferablyrcentrally thereof, in any approved relation. All of the spars 23 to 26 inclusive and SO'and 31 are in the same plane, and they are coveredby some material 32, such as fabric. f 'lhis prevents eddies of air current about the spars, and forms a sort of vertical plane to divide the air stream between the portions of the provided with perpednicularside planes 35 and 36, in right angled relation to the plane 20 and parallel to the vconstruction 21. These side planes are mainly used Vfor directing the flow of air under lthe plane 20, and to prevent side slip. It is to be noted that the width of the main sustaining plane 2O is not much greater than' themaximum width of the fuselage B. l

The sustaining plane construction terminates short of the fore end of the fuselage.

An engine 40 actuates a vertical propeller 41,A which operates as a. tractor sc-rew to draw.

the aeroplane thru the air. The engine 40 is supported4 by means 42 on the forep'art of the Vfuselage and the slip stream from the propeller is entirely disposed below the plane of the wing 20. A motor 44 of the construction D is provided on the fore part Yof the fuselage, having a vertically disposed preferably hollow sha-ft 45, which it operates, and which extends upwardlj.7 lt is preferably a six inch hollow duralumin shaft, and has a horizontal propeller 4'? at the upper end thereof, at a location immediately above the plane of the wing-20. This shaft 45 is supported at yits upper end by means of the for-l lwardly projecting end ofthe main sup- 50VV porting beam 28 of the wing 20, which has y an anti-friction bearing 51 for such support of the shaft. If desired, guy wires 52'may extend from the shaft yor theV anti-friction bearingA 51 to the corners of the wing 2O for rudderarrangement, consisting of rudders 54 and 55, which arev vertically hinged at 56 to the rear edges of the side wings 35 and 36.

lf desired, the vertical rudder arrangement may be connected to the spar 21.' A horizontal control or elevator 57 is provided, for

controlling vertical flight; thisk elevator 57 being pivoted at 58 to the rear of the plane 20.

While Vno attachment for control of laterali Ver-V is fiat.

stability has been provided, should it be found desirable to include such feature, they are merely'of conventionaly design and can'be .i

added.

It is to be noted that thewing or plane20 kWith such a flat" plane, v,when it 'Y vreaches zero angle of incidence, the pressure i movesxoflthe plane at approximately 25% from the leading-edge. Therefore, in this V j invention such pressure wouldmove .od the plane atfapproximatelyv the location desig-k v nated at 60 in Figure 1 of thedra-wings. Ing

"order to lproperly stabilizethe craft, the center of-gravitylof the machine, designated at 61 in Figure 1, is locatedfslightly rearl wardly of-a perpendicular line dropped from t the, location 60. i .n vUpon setting the machine in motion along the ground, by means' of' operation of the propeller 471, the tail partl of the machine willbe'depressedand a center of pressure will develop at a point between 60 and the center ofthe. plane 20.1- Asthe speed of the d Y propeller 41 increases, the machine will liftv off the ground, but atia'great expense of power, due to lthe excessive amount of' dragV as compared withlra cambered plane. Further` increasing the speed' of Vthe propeller 41 permits the center of the pressure to be moved forward and the angle of incidence decreases,

and; also the4 drag.l Itfollows,that in this Y type of'plane, then liftV decreases and the machine begins to descend. With the maf Y Y chine viiying and the plane 2O at practically f ero angle of incidence, the center 'ofy pres`` Y.

sure is approximately attire-location 60,v and the'center of'gravity therebelow. The machine vis now in a condition of linherent stability, because a depression of the tail moves the center of pressure tothe rear and sets up 1 a`rightingcouple on the under surface of the plane. YA depressionof the leading edge cor-f respondingly will move the center of pressure top side of the plane.

machine to4 the ground, unless a new principle of'flight is brought into operation. My claim for a-sustained flightY by an aeroplane .lof this type, using flat planes is vbased on utilization of cemparatively great speeds.

The above described gliding flight yof the machine A, at a certain speed, assumes that the air is constantlyl displaced. However,

as it takes a certainv amount of time forrthe air to be compressed and displaced, it is my air and leaving vbehind the air already `to the krear and setup a righting couple on the Y This condition ofA Vstable gliding flight would soon bring the travelled over, 'at ars'peed so rapid that theV air does not have time to be compressed and displaced, and the yplane orplanes will haveY no angle of incidence, and no under side pres-y sure o r top's1del suction as has been necessary lli for sustainedflig'ht of aeroplanes heretofore.

l This will be entirely feasible when high speed engines are developed to the'extent possible V `to bring the use of my construction kinto practical operation'. V

11; With the improvementsvfin construction below described, the aeroplane is capable of heavier loading and flying at less speed. vThis is so because the motor 44 operates the propeller 47 so as to force the current offair into which the plane jis about to passto a Y location below the plane 20. Thus, as'the aeroplane moves forward the `upper surface ofthe plane 20l enters a portion of the air which has been rarefied by the suction of the propeller 47 and the downward stream of air from the propeller 47 is caught in theslip Vstream of the propeller 4l and blown backward beneath the plane 21, increasing the 20'" density of air under the plane 20. This decrease'of densityabove the plane 20 and in-y y creaseof density below the plane20 creates a lift which is obtained kwithout the detrimental drag associated with planes of the cambered type. yIn this connection the 'lateral planes 35 and 36 'are of great value inv directing the air rearwardly beneath bthe long narrow main plane 20. v

The operatioiiof thepr'opeller 47 lcreates a lifting eii'ect on the forward part of the a' laeroplane which tends to move the center of rpath with practically no angle of incidence; [All this is accomplished without use of the gravity towards the rear. Thisfwould create anoifsetting coupleif it were not for the facttliatY the combined efforts of propellers 4l and 47 move the center of pressure to the reary also. By proper adjustment ofthe .rela-` tive speeds of the motors the aviator can con trol the aeroplane for 'horizontal flight'by rbringing the center of pressure and the center of'gravity into proper relation, and atthe same time maintaining the plane on its flight elevator 57. Aeroplanes in common use requireadjustment of the elevator and consequent Achanges in the vangleof incidenceto Y 5o*l i plane.

compensate for speeds 'or loadings other than l 'thoseprovided for in the design of the aircraft. These changes create greater drag,

which is not the casefwith my improved aero- However, an elevator 57 is provided foriiseon the improved aircraft A, because temporary correction of flight .path will .at 1 [times be necessary. f 55 The improved aeroplane A ,be manipu- [lated'to bank itself on turns without the aid of ailerons, because of centrifugal force act# ing on the center of gravity in much the same manner that trains suspended by a. niono- Vrail swing out on curves. The perpendicular gicle planes 35 and 36 act to prevent side slip ',-in this connection, andfurther safeguard is enabled by reason of the lateral rudders 54 yand 55. v' i An important feature in the designof any a the helicopterclass.

heavier than air craftisthe ability plane to 'make va safelanding whetlier `the y motors are operating or not. Assumingthat motor 44 should cease to function, the opere ator could of courseuse motor 40 and the vertical propeller 41. AShould motor 40 `stop operating@y Vproper regulation Vof" the',` motor 44 for operation of the propeller 47 and in connection with operation of the elevator 57, willenable a'safe landing by means of a slow glide. lf both motors cease tofunction `it is noted that the `location of the centerfof gravity' 6l and the centerof pressure at 60 provides a machine with inherent stability vfor aisafe'and rathery fast glide'to safety.

lt is fairly practical to use a longer/inse-y lage for the air craft A, and therewith a series fof flat planes inthe same line of flight with yeach other, with thetrailing and lead# ingedges ofthe planes separated by means lOfa space.` i. i f c y Briefly, from the foregoingitmay. be seen that the main difference vbetween common heavier than air craft 'and my invention-'is the yprovision vofan aircraft which is practical for use with high speed"engines,`in

which the main sustaining wings are not cambered, but are flat and intended to be po# sitioned at no angle of incidence, during flight, to prevent air compression therebelow. However, my improved aircraft 1s also novel,

since it maybe used in-.connection with proy peller operation by means of which a rareed I condition is secured above the' plane and` a compressed condition below the vplane in a manner different than anything heretofore provided, to my knowledge. This relationship may or may rnot l'be used in connection with a flat wing, such as Iprovid'e, but I f prefer to use a flat wing,'without depending operating from preferably the same engine in in: v

lno

a synchronized relation by means of suitable transmission mechanism; one such horizontal propeller being disposed on the starboard side of the craft and having a right hand screw action, and another horizontal propeller bepellers may balance each other to -prevent ing disposed in a synchronizingoperation at the port side, and having a left hand screw action. Thus, these two horizontal proeccentric;fightg-ffmy -Will be disposed opf: posite each otherjtransversely ofthe slip. Y .L Various changes', in the shape, size7 and arrangement of parts may be made to theA formV of 'invention yherein shown! ,and` described, Without departing freni-,the spirit of the invention orfthe'scope of the claims.- lam': f' Y '1. ;Aheavierthan air craft comprising 'a im fuselage,-a single flat sustaining'plane extend-A ingfy throughout substantially the entire 'lengthof the fuselage andfdisposedabove the Y fuselage; andy being i relatively narrow..v and free-of horizontal lateral 'sustaining 'Wings .V15 andin.vvhichthey oentenofpressure Willbe ata'point approximately one quarter the distance fromthefleading'edgethereof When the l plane 'is at Ysubstantially zeroangle k0ffincin denc'e,"-the center of gravity ofthe craftbeing .20 disposed belowtheplane and to therear of "a line perpendicular from a point ,one-quanl ter tlie distance from the leading` edge ofthe `plane',fand driving means includingja prop'eller' carried bythe fuselage'entirelyy for- '25* validly of theplane.l

body'having a planeV supported thereab ove by -means' of a relatively thin upstanding strut Y construction supported along the longitudi- 30 nal centerof the fuselage5 said'strut constructionconiprising acovered plane, the .first A mentioned plane construction beingslightly f l`Widerthanfthe fuselage and extending sub.; stantially the entire'len'gth ofthe fuselage; Vvfig- 35 and'dependingV side W'ingstransversely upon and along the side edgesof the inain plane.

'8l A Vheavier than air craftcornprisinga body having al plane supportedthereabove by -niean's of a*relativelyf'thinYupstanding strut 4p construction supported along the longitudif nal center of the-fuselage, said strutv con'- stru'ction comprising a covered plane andthe first"mjentioned Vplane vconstruction being slightly Wider than the fuselage andextend# Y 145 ing substantially the entire lengthof the fuselage, depending^side Wings transversely -upon and along the side edgesfof the main plane;V y ru'dders'hinged'on the -rearfedges of-said side Wings,1and an elevatorf atthe rearedge of- 59 the main plane. 'f I Y si.. j i y on Y HAROLD C.PRATT,

kQAfheavier than air craft oonoprisinga l l* AK r. I' 

